This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. CTX-M beta-lactamase is a new group of class A beta-lactamase that has emerged world-wide in the past ten years. The crystals of CTX-M enzymes diffract to sub-[unreadable]ngstrom resolution, permitting the determination of alternate conformations and hydrogen atom positions. Such information is of great value to identifying general base/acid roles for catalytic residues and to obtaining an accurate protein template for molecular docking. Previous experiments at ALS Beamline 8.3.1 were limited by the size of the image plate and we were not able to collect diffraction data below 0.85 [unreadable].